FIELD OF THE INVENTION
This invention relates to hose and hollow member arrangements. The invention is particularly concerned with flexible hoses and hollow members to which they are to be fitted for use in turbocharged motor vehicle engine installations.
It has been required to provide more power in vehicles as permitted vehicle weights have increased over the years. A well known method of doing this is to turbo- charge the engine so that air under pressure is supplied to the cylinders to provide more complete combustion and more power than is available by taking air into the cylinder at atmospheric pressure. Air delivered to the engine by a turbocharger has its temperature raised considerably because the turbocharger is driven by engine exhaust gases and the heat from these passes to the turbocharger compressor portion which delivers the air to the engine. This heating effect reduces the engine efficiency somewhat so that not all of the extra power theoretically available is achieved. To combat this intercooling has been used. This entails passing the turbocharged engine intake air at its higher pressure and temperature through a heat exchanger where it is cooled before it is introduced into the engine cylinder for combustion.
It is very common for turbocharger and intercooler interconnections and connections to the engine intake system to be made by silicone rubber hoses. This allows relative movement to be economically accommodated and also allows the easy achievement of complex hose shapes which are sometimes necessary due to overall engine compartment design considerations. These silicone rubber hoses are fitted over parallel metal pipework both on the turbocharger and intercooler and on the engine intake system and are secured with worm drive clamps and clips.
As higher power outputs are sought from existing engines, the turbocharged air pressures are increasing. Typical current values of 1-2 bar (gauge) may be increased to 3-4 bar (gauge) and even higher. At these elevated pressures the previous method of fixing using worm drive clamps becomes unreliable and leads to excessive amounts of leakage. Merely increasing the torque of the fixing will not reduce the leakage as it will lead to damage of the hose which in turn can lead to increased leakage.